Solar plus battery is the fastest growing home energy product. This guide covers when battery makes sense, what to check before buying, and how to size the system for your household.
How solar plus battery works
Solar panels generate DC electricity during daylight. Hybrid inverter feeds home load first, then battery, then grid (or reverse depending on tariff). At night, battery discharges to serve home load; grid backup handles anything beyond battery capacity.
When is battery worth it
| Situation | Battery makes sense |
|---|---|
| High grid rate, low export rate | Yes to self consume |
| Time of use tariff | Yes to arbitrage peak |
| Frequent grid outages | Yes for resilience |
| Off grid | Yes, essential |
| Simple net metering | Marginal on economics |
| Very low grid rate | No, hard to pay back |
Sizing the battery
Match battery capacity to evening and overnight consumption. Typical home battery is 10 to 15 kWh, which covers most homes overnight.
Battery brands
- Tesla Powerwall (leader by market share).
- LG Chem RESU.
- Enphase Encharge.
- Pylontech (widely deployed globally).
- BYD (China leader).
- Sonnen (Germany).
Cost
Battery adds USD 8,000 to 15,000 to a solar installation. Cost per kWh installed USD 500 to 1,000. Falling but slower than pure solar.
Backup power capability
Not all home batteries support backup during grid outage. Ask specifically: whole home backup, essential circuits, or no backup. Requires disconnection from grid during outage (automatic transfer switch).
Battery warranty
Standard warranty 10 years covering 70 to 80 percent remaining capacity. Cycle limits or throughput limits often included. Read carefully.
Incentives
US IRA 30 percent tax credit applies to solar plus battery (battery over 3 kWh). State and local rebates vary. Some utility programmes provide additional incentive.
Installation considerations
- Location: garage typical, some indoor and outdoor rated.
- Ventilation: sufficient airflow for thermal management.
- Distance from inverter: DC loss over long runs.
- Safety: fire suppression, thermal runaway protection.
- Permits: often more complex than solar alone.
- Interconnection: utility approval typically required.
Time of use optimisation
Modern hybrid inverters can schedule battery charge and discharge based on tariff. Charge from grid during off peak, discharge during peak. Depending on tariff differential, this can add substantial revenue.
Questions to ask installer
- What battery capacity fits my consumption?
- What backup circuits are supported?
- What tariff optimisation does the inverter support?
- What is the warranty coverage?
- What if the battery fails at 8 years?
- Is the battery covered under home insurance?
- What if my utility changes tariffs?
Virtual power plants
Some utilities aggregate home batteries into virtual power plants (VPPs) that provide grid services. Participation typically pays USD 100 to 500 per year to the homeowner. Growing programme in several markets.
Where home solar plus battery is going
- Continued cost reduction.
- Better tariff optimisation software.
- VPP participation programmes.
- Vehicle to home integration with EVs.
- Heat pump plus battery integration.
- AI energy management.
Frequently asked questions
Do I need a battery for solar?
No. Solar without battery works fine with net metering.
Will battery keep power during outage?
Yes if system is designed for backup. Depends on installer choice.
How long can battery run my home?
10 to 15 kWh typically covers overnight for most homes. Longer outages need more capacity.
How long do batteries last?
10 to 15 years typical warranty.
Is battery safe indoors?
Modern LFP batteries are safe indoors with proper installation.
What about warranty coverage?
Typically 10 years covering 70 to 80 percent remaining capacity.
Can I add battery later?
Often yes if hybrid inverter installed. Retrofit is possible.
Does battery affect solar warranty?
Verify installer includes both in single warranty scope.
How much money does battery save?
Depends on tariff. Ranges USD 200 to 1500 per year of net savings.
Should I participate in VPP?
Depends on programme terms. Additional income but constrains battery use.
Summary
Home solar plus battery is a mature product. Battery makes economic sense with high grid rates, time of use tariffs, or frequent outages. Typical 10 to 15 kWh battery costs USD 8,000 to 15,000 additional. Payback longer than pure solar but adds resilience. Ask installer specific questions about capacity, backup, and warranty. Consider VPP participation programmes.
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